EP0648036A1 - Burst-Mode Empfänger mit differentieller Demodulation - Google Patents

Burst-Mode Empfänger mit differentieller Demodulation Download PDF

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Publication number
EP0648036A1
EP0648036A1 EP94113282A EP94113282A EP0648036A1 EP 0648036 A1 EP0648036 A1 EP 0648036A1 EP 94113282 A EP94113282 A EP 94113282A EP 94113282 A EP94113282 A EP 94113282A EP 0648036 A1 EP0648036 A1 EP 0648036A1
Authority
EP
European Patent Office
Prior art keywords
signal
adaptive filtering
instant
filtering means
output
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP94113282A
Other languages
English (en)
French (fr)
Inventor
Antonio Del Pino Juarez
Fidel Garcia Pedraja
Antonio Escuela Superior De Artes Rodriguez
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nokia Spain SA
Original Assignee
Alcatel Standard Electrics SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alcatel Standard Electrics SA filed Critical Alcatel Standard Electrics SA
Publication of EP0648036A1 publication Critical patent/EP0648036A1/de
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
    • H04L25/03019—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception
    • H04L25/03038—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception with a non-recursive structure
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission
    • H04L2025/03375—Passband transmission
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/03433—Arrangements for removing intersymbol interference characterised by equaliser structure
    • H04L2025/03439—Fixed structures
    • H04L2025/03445—Time domain
    • H04L2025/03471—Tapped delay lines
    • H04L2025/03477—Tapped delay lines not time-recursive
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/03592—Adaptation methods
    • H04L2025/03598—Algorithms
    • H04L2025/03611—Iterative algorithms
    • H04L2025/03617—Time recursive algorithms

Definitions

  • This invention concerns a digital radio receiver that receives a bandpass signal with phase modulation and which, without recovering the carrier, regenerates the transmitted data by means of baseband differential demodulation from the in-phase and quadrature components previously equalised to compensate for linear distorsion produced in the communications channel.
  • the antenna of the central station is usually of the omnidirectional type since the terminal equipments can be distributed over a determined area whereby, although these terminal equipments have directional antennas, the received signal, both at the central station and by the terminal equipments, is usually subject to selective fading which notably deteriorates the quality of the received signal.
  • equalizing circuits In order to overcome this impairment and assure the quality of the communications, equalizing circuits are employed that have a variable transfer function that depends on internal parameters, and the purpose of which is to compensate for the linear distorsion of the communications channel over which the signal is transmitted, so that this signal does not suffer channel impairment.
  • differential demodulators are used.
  • the block diagram of a baseband differential demodulator can be seen in the article "Implementation of Coded Modems" by Shuzo Kato et al., IEEE COMMUNICATIONS MAGAZINE, December 1991, pages 88 to 97.
  • the frequency error in the local oscillators must, in any case, be limited to a value that makes the extra phase shift produced in a bit period, as a consequence of this error, insignificant when compared with the phase shift caused by the modulation.
  • the burst receiver of the invention receives a bandpass input signal that is divided into two other signals by means of a divider in order to feed frequency conversion means that produce at its output two lowpass signals, one in-phase and one in quadrature, which are sent to decision means for comparison of the previous values with reference values and to produce an output data signal with adequate shape and levels.
  • This receiver is characterised in that between the frequency conversion means and the differential demodulation means, adaptive filtering means are connected to perform a pre-filtering of the in-phase and quadrature lowpass signals in order to compensate for the linear distorsion of the communications channel.
  • the receiver according to the invention is characterised in that the aforementioned adaptive filtering means receive the output data signal, the demodulated signal and a signal that is its own output signal but delayed by one symbol period. All the preceding signals are used by the adaptive filtering means mentioned in order to update its filtering coefficients.
  • the differential demodulation does not require carrier recovery and is applicable to phase modulation systems, in which the phase difference in a symbol period indicates the symbol transmitted.
  • This procedure can be done at an intermediate frequency but it is also possible to do it in baseband starting from a complex envelope, that is, from the equivalent in-phase and quadrature signals, as is shown in figure 1.
  • the input signal S is split, by means of a divider 1, into two equal signals that are applied to frequency conversion means 2, the composition of which is already known according to the state of the art, and which consists of a free-running oscillator 24 at the same frequency as the carrier of the input signal S, a 90° phase-shifter circuit 23 in order to change the phase of the signal coming from the free-running oscillator 24, and two multipliers 21 and 22 that multiply the two samples of the input signal S by a signal coming from the free-running oscillator 24 and by a version of this last signal shifted in phase by 90° in a phase-shifter circuit 23.
  • the output signals from both multipliers are filtered in respective low-pass filters 25 and 26 in order to obtain the in-phase and quadrature low-pass signals, Is and Qs, that correspond to the complex envelope of the input signal S with a slight frequency error determined by the frequency difference between the carrier of the input signal S and that produced by the free-running oscillator 24.
  • the aforementioned in-phase and quadrature low-pass signals Is and Qs are applied to differential demodulation means 4 for demodulation, the outputs of which, in turn, are applied to decision means that produce the output data signals Di and Dq, corresponding, respectively, to the in-phase and quadrature paths.
  • both in-phase and quadrature low-pass signals, Is and Qs are applied to adaptive filtering means 3 which comprise, as is known from many technical publications, a transversal filter whose coefficients form a complex vector, termed W, which vary according to quadratic error minimising criteria.
  • the output signal from the adaptive filtering means Rc is applied to differential demodulation means 4, of known configuration, formed by multiplier circuits 43 that multiply the output signal from the adaptive filtering means Rc by a version of this signal but delayed by one symbol period in a delay circuit 41 and shifted in phase by 90° in a circuit 42 that forms the conjugate.
  • the output signal generated by said differential demodulation means 4 is the demodulated signal Rd that is sent to decision means 5 in order to produce the output data signal D.
  • the adaptive filtering means 3 consist of a transversal filter, as stated above, with a certain number of stages, so that there is also a complex vector, to be termed R ⁇ , the components of which are the values of the compound incoming signal formed by the two in-phase and quadrature low-pass signals, Is and Qs, for each of the sampling stages of the transversal filter.
  • W ⁇ (K+1) W ⁇ (K) + ⁇ [e (K) . Rt. R ⁇ * (K) + e* (K) . Rc. R ⁇ * (K-1) ].

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
EP94113282A 1993-10-08 1994-08-25 Burst-Mode Empfänger mit differentieller Demodulation Withdrawn EP0648036A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ES9302130 1993-10-08
ES9302130A ES2079294B1 (es) 1993-10-08 1993-10-08 Receptor a rafagas con demodulacion diferencial.

Publications (1)

Publication Number Publication Date
EP0648036A1 true EP0648036A1 (de) 1995-04-12

Family

ID=8283278

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94113282A Withdrawn EP0648036A1 (de) 1993-10-08 1994-08-25 Burst-Mode Empfänger mit differentieller Demodulation

Country Status (7)

Country Link
EP (1) EP0648036A1 (de)
CN (1) CN1118539A (de)
AU (1) AU678032B2 (de)
ES (1) ES2079294B1 (de)
NZ (1) NZ264416A (de)
PL (1) PL174750B1 (de)
RU (1) RU94036446A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9112754B2 (en) 2013-10-08 2015-08-18 Freescale Semiconductor, Inc. Techniques for generating bit log-likelihood ratios in communication systems using differential modulation
CN105510653A (zh) * 2015-12-07 2016-04-20 国网天津市电力公司 一种基于自适应最小均方算法的正交信号发生器系统

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0376250A1 (de) * 1988-12-30 1990-07-04 Alcatel Telspace Selbst-adaptive Entzerrungseinrichtung für eine differentielle kohärente Demodulationsanordnung
EP0524560A2 (de) * 1991-07-26 1993-01-27 General Instrument Corporation Of Delaware Verfahren und Einrichtung zur Aktualisierung der Koeffizienten eines komplexen, adaptiven Entzerrers

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL186990C (nl) * 1979-03-16 1991-04-16 Philips Nv Zelfinstellend filter met een vertragingsschakeling.

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0376250A1 (de) * 1988-12-30 1990-07-04 Alcatel Telspace Selbst-adaptive Entzerrungseinrichtung für eine differentielle kohärente Demodulationsanordnung
EP0524560A2 (de) * 1991-07-26 1993-01-27 General Instrument Corporation Of Delaware Verfahren und Einrichtung zur Aktualisierung der Koeffizienten eines komplexen, adaptiven Entzerrers

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9112754B2 (en) 2013-10-08 2015-08-18 Freescale Semiconductor, Inc. Techniques for generating bit log-likelihood ratios in communication systems using differential modulation
CN105510653A (zh) * 2015-12-07 2016-04-20 国网天津市电力公司 一种基于自适应最小均方算法的正交信号发生器系统
CN105510653B (zh) * 2015-12-07 2018-11-06 国网天津市电力公司 一种基于自适应最小均方算法的正交信号发生器系统

Also Published As

Publication number Publication date
AU7165694A (en) 1995-05-11
PL174750B1 (pl) 1998-09-30
CN1118539A (zh) 1996-03-13
NZ264416A (en) 1997-05-26
PL305353A1 (en) 1995-04-18
RU94036446A (ru) 1996-08-27
ES2079294A2 (es) 1996-01-01
ES2079294B1 (es) 1997-06-01
ES2079294R (de) 1996-11-01
AU678032B2 (en) 1997-05-15

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